<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    用户名： <input type="text" id="user" />
    <script>
      var userEle = document.getElementById('user')

      // 监听内容改变事件
      userEle.addEventListener('input', function () {
        console.log('input')
        // console.log(this.value)
      })

      userEle.addEventListener('change', function () {
        console.log('change')
        // console.log(this.value)
      })
    </script>
  </body>
</html>
